There are many applications including (but not limited to) decorative lighting, entertainment lighting, signage, and general lighting in which individual lights or groups of lights are to be controlled independently of each other to produce a variety of lighting effects. Light emitting diodes (LEDs) are particularly well suited to these applications because of their low power consumption, small size, and fast response time. One possible control topology is to connect and control a series of LEDs using a serial data bus.
Current serially controlled lighting systems employ inefficient addressing methods, which include hardware intensive decoding of predefined addresses or time consuming address processing and determination algorithms. Examples include those disclosed in U.S. Pat. Nos. 6,777,891; 7,462,103; and 7,605,547; each of which is incorporated by reference into this application for their disclosure of general principles and terminology.
U.S. Pat. No. 6,777,891 discusses a method of addressing nodes on a serial data bus which does not require pre-assignment of addresses to the various nodes, but the packet structure is very inefficient, as it requires each packet, when transmitted by the master bus controller, to contain a field for every node on the bus. Each node then strips one field off the packet before forwarding it to the next node. Packets are thus large and therefore require more time to traverse the bus. Also, nodes cannot be addressed randomly since each packet must contain a field for each node on the bus.
U.S. Pat. No. 7,462,103 discusses an addressing method similar to that of U.S. Pat. No. 6,777,891; only in the case of this patent the various nodes on the serial data bus are treated as shift registers. Each packet contains a field for each node on the bus, but the packet does not become any shorter as it traverses the bus. As for U.S. Pat. No. 6,777,891, nodes cannot be addressed randomly since each packet must contain a field for each node on the bus.
U.S. Pat. No. 7,605,547 discusses a method of addressing nodes on a serial data bus which requires each node to have its particular address set in hardware, by switches, jumpers, or other means. This method supports random addressing. However, since each node's address must be configured in hardware, this method is poorly suited to systems which contain many nodes.
None of the mentioned patents contain any provision for detection of or compensation for conditions of excessive current draw by the various nodes. Neither do any of the mentioned patents contain any provision for detection of or compensation for conditions of excessive heat generation by the various nodes.